The reactions of neutral ground-state yttrium (Y) atoms with 1,3- and 1,4-cyclohexadiene (CHD) were studied using crossed molecular beams. Formation of YC6H6 + H-2 and YH2 + C6H6 was observed for both isomers at collision energies (E-coll) of 31.3 and 13.0 kcal/mol. Measured product branching ratios at E-coll = 31.3 kcal/mol indicated that YH2 + C6H6 was the dominant channel, accounting for > 97% of the products. An additional minor product channel, YC4H4 + C2H4, was observed for 1,3-CHD at the higher E-coll. The reaction threshold for YC4H4 formation was determined to be 29.5 +/- 2.0 kcal/mol based on fits to the data.